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首页> 外文期刊>Journal of Systematic Palaeontology >Early dinosaurs: a phylogenetic Study
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Early dinosaurs: a phylogenetic Study

机译：早期恐龙：系统发育研究

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Early dinosaur evolution has been the subject of several phylogenetic studies and the position of certain basal forms is currently debated. This is the case for the oldest known members of the group, excavated from the Late Triassic Ischigualastian beds of South America, such as Herrerasaurus, Eoraptor, Pisanosaurus, Saturnalia and Staurikosaurus. A new cladistic analysis of the early dinosaur radiation was performed to assess the relationships among the three major clades (Ornithischia, Sauropodomorpha and Theropoda) and to define the phylogenetic position of the basal members of the group. The most parsimonious hypothesis has Silesaurus opolensis as the sister taxon to a dichotomy including monophyletic Saurischia and Omithischia. The latter includes Pisanosaurus mertii, and the former all other well-known Triassic dinosaurs. Saurischia is composed of two major monophyletic groups: Herrerasauridae (including Herrerasaurus ischigualastensis and Staurikosaurus pricei) and Eusaurischia (including the theropod and sauropodomorph lineages), while Eoraptor lunensis appears to represent the sister taxon to Eusaurischia. Saturnalia tupiniquim is a stem-taxon to Sauropodomorpha and Guaibasaurus candelariensis might belong to the theropod branch. Some of these hypotheses are, however, not strongly supported. Especially uncertain are the affinities of Silesaurus and Guaibasaurus. The latter can only be safely regarded as a saurischian, while the former might belong to the ornithischian lineage. The dinosaurian affinities of Eoraptor and Herrerasauridae are strongly supported. Yet, the possibility that they (especially Eoraptor) represent basal theropods, rather than basal saurischians, cannot be dismissed. In fact, basal saurischian evolution is still too poorly understood for a definitive hypothesis of relationships to be presented.
机译：早期的恐龙进化已成为一些系统发育研究的主题，并且目前正在讨论某些基础形式的位置。这是该组中最古老的成员的情况，这些成员是从南美晚三叠世的伊斯基瓜拉第斯河床发掘出来的，例如海雷龙，Eoraptor，Pisanosaurus，Saturnalia和Staurikosaurus。进行了一项新的早期恐龙辐射的分类分析，以评估三个主要进化枝（鸟眼，Sauropodomorpha和Theropoda）之间的关系，并确定该群体基础成员的系统发育位置。最简约的假说是将Seosaurus opolensis作为二分法的姊妹分类群，其中包括单生的毛毛线虫（Saurischia）和奥米奇虫（Omithischia）。后者包括野生三角恐龙（Pisanosaurus mertii），以及其他所有著名的三叠纪恐龙。毛uri属由两个主要的单系组成：埃雷索龙科​​（包括埃雷索龙属和石蒜科）和欧亚毛sch属（包括兽脚亚目和兽足类谱系），而轮虫（Eoraptor lunensis）似乎代表了欧氏毛sister的姊妹分类群。 Saturnalia tupiniquim是Sauropodomorpha的茎分类单元，而Guaibasaurus candelariensis可能属于兽脚亚目。但是，其中一些假设并未得到大力支持。 Silesaurus和Guaibasaurus的亲和力尤其不确定。后者只能被安全地视为saurischian，而前者可能属于鸟眼鸟血统。强烈支持Eoraptor和Herrerasauridae的恐龙亲和力。但是，不能排除它们（尤其是Eoraptor）代表基底兽脚亚目而不是基底蜥脚类动物的可能性。实际上，对于基础的萨里斯基进化论，仍然很难理解，无法给出明确的关系假设。

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